JP2001174351A - Pressure sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensor invariably securing high measurement precision, reducing the change, deformation, and others of a measurement signal based on thermal expansion to the minimum level, having high reliability and durability, and relatively easy to manufacture at a low cost. SOLUTION: This pressure sensor 1 is used for an extruding machine of a plastic material in particular, a chemical process, and others. The pressure sensor 1 is provided with a support element 3 for a semiconductor chip 5 having a strain gauge 9 on one of opposite faces, a casing 2 suitable to store the support element 3, a cover element 6 provided to close the casing 2, and a mechanical transfer element 8 stored in the cover element 6, faced to the semiconductor chip 5, and kept in contact with the semiconductor chip 5. The semiconductor chip 5 is stored to float in the support element 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-precision pressure sensor. In particular, the invention relates to a pressure sensor applied to detect the pressure in an extruder of plastic materials, plastic films, synthetic fibers and the like.

[0002]

2. Description of the Related Art For example, a pressure sensor used in an extruder for a plastic material, a plastic film, a synthetic fiber, and the like is such that a thin film having a surface on which a strain gauge is disposed includes a rod-shaped element at one end. It has been known. Such a rod is filled with a fluid, such as mercury or oil, and the compression of that fluid by the mass of the plastic material whose pressure is to be measured acts on the strain gauge, so that the strain gauge is connected to the electronic sensor connected to its pressure sensor. Generate electrical signals that are processed by the system.

[0003] A disadvantage of this pressure sensor is that, due to its limited thickness, the molten plastic material easily damages the thin film and quickly becomes exhausted. Therefore, pressure sensors need to be replaced, and above all this requires the disposal of mercury or oil, for example mercury is highly contaminating and strict standards must be adhered to for its disposal. With unacceptable costs.

In addition, it is known that the pressure sensor is constituted by a bar having one end with an element for mechanically transmitting pressure acting on a chip of semiconductor material, on one side of which a strain gauge is arranged. Have been. actually,
The semiconductor chip behaves like the thin film of the sensor described above. The presence of semiconductor chips solves the problem of fluids such as mercury or oil that are no longer needed.

[0005] Semiconductor chips are usually housed in suitably provided cavities formed in blocks made of, for example, alumina, from which the strain gauges lead to electronic systems for processing signals. There are a number of metallized terminals that are adapted to carry signals. These sensors have a semiconductor chip that is firmly bonded to the alumina block, for example, by being fixed.

[0006] The mechanical transmission element is usually housed in a cover. The cover is adapted to be coupled to a metal enclosure that houses an alumina block having a correspondingly bonded semiconductor chip firmly attached thereto.

[0007]

The advantage of this solution is that in this case the thin film composed of chips of semiconductor material is not substantially exposed to wear due to friction with the plastic material whose pressure is to be measured. It is.

[0008] However, the fact that the semiconductor chip is firmly bonded to the alumina block that supports it,
The problem remains that the signal generated as a result of the pressure detection may be incorrect. This is because there are deformations that may affect the alumina block that houses and supports the semiconductor chip.

For this reason, even the above-mentioned solution to the problem does not solve the drawback, and in particular, the measurement accuracy, which is a basic requirement, is not absolutely secured. The aim of the present invention is to provide a pressure sensor which always ensures high measurement accuracy and which is particularly suitable for extruders of plastic and similar materials.

[0010] Within this aim, one of the objects of the present invention is to provide a highly durable pressure sensor. Another object of the invention is to use, in particular, extruders for plastics and similar materials, in which the change, deformation and the like of the measuring signal due to thermal expansion are reduced to the lowest possible level. It is to provide a sensor.

Another object of the present invention is to provide a pressure sensor which is particularly reliable for use in extruders for plastic materials and which is highly reliable, relatively easy to manufacture and low in cost.

[0012]

SUMMARY OF THE INVENTION The above objects and objects, which will become apparent hereinafter, are adapted to accommodate a support element for a semiconductor chip having a strain gauge on one of the opposite surfaces and to accommodate the support element. And a cover element provided for closing the outer enclosure, and a mechanical transmission element housed within the cover element and directed to the semiconductor chip and in contact with the chip. The pressure sensor is characterized in that the semiconductor chip is housed in a floating manner in the support element.
The pressure sensor according to the invention is particularly suitable for use in plastic material extruders, chemical processes and the like.

In a preferred embodiment of the present invention, the mechanical transmission element housed in the cover element may be housed so as to float in a sheet formed in the cover element.

The support element comprises alumina, and the support element has a plurality of conductors extending from the support element, the conductors being adapted to transmit a pressure signal detected by the strain gauge; The strain gauge may be disposed on one surface of the semiconductor chip opposite to a surface on which the mechanical transmission element operates, and the mechanical transmission element operates on the mechanical transmission element. The semiconductor chip may be housed in the cover element so that a load is applied to the surface of the semiconductor chip in advance. The semiconductor chip may be made of silicon carbide (SiC), SOI (SiliconOn).
Insulator) or SOS (Silicon On Sapphire).

[0015]

Further features and advantages of the present invention will become more apparent from the following detailed description of preferred but non-limiting embodiments of the pressure sensor according to the present invention. This embodiment is described by way of example only and not by way of limitation in the scope of the accompanying drawings, the sole figure of which is a cross-sectional view of an end of a pressure sensor implemented in accordance with the present invention.

As shown in the above-mentioned drawings, in the pressure sensor according to the present invention, a portion according to the present embodiment is generally indicated by reference numeral 1, and as will be described later, a seat for accommodating a semiconductor chip 5 is provided. ) 4 having an outer enclosure 2 adapted to receive a support element 3.

The support element 3 is preferably provided by an alumina block, in the drawing of the block of which a plurality of metal conductors 10 extend downwardly from the lower surface, the metal conductors 10 being connected to a sensor according to the invention. A signal generated by the semiconductor chip 5 is transmitted to the system. That is, the semiconductor chip 5 and the metal conductor 10 are
It is connected via an electronic system (not shown).

The supporting element 3 has a lower surface provided with a reference electrode 11 extending downward, a metal conductor 10 and the reference electrode 1.
1 is fixed to a cylindrical body 12 surrounding the cylindrical body 1. Reference electrode 11
Is connected to the semiconductor chip 5 via the electronic system (not shown), and is provided for compensating the influence of the ambient temperature and pressure on the semiconductor chip 5. The cylindrical body 12 has a skirt shape spreading downward,
For supporting the support element 3.

Reference numeral 5 denotes a semiconductor chip adapted to be accommodated in the sheet 4 formed on the support element 3. The semiconductor chip 5 floats inside a seat (seat) 4 defined within the support element 3. This means that the sheet 4 is slightly larger than the diameter of the semiconductor chip 5 and that the semiconductor chip 5 can move slightly in the sheet 4 and the semiconductor chip 5 is in contact with the bottom of the sheet 4 I do.

[0020] The cover element 6 comprises an enclosure 2 like a cover.
Is provided above the outer enclosure 2 to close the enclosure.
The cover element 6 has a sheet 7 which houses a mechanical transmission element 8, which exerts a pressure on the semiconductor chip 5 when a flow of plastic material strikes the upper surface of the cover element 6. It is designed to work. The strain gauge 9 is mounted on the surface of the semiconductor chip 5 opposite to the surface on which the mechanical transmission element 8 acts.

A feature of the pressure sensor 1 according to the present invention is that the semiconductor chip 5 is accommodated so as to float in the sheet 4 of the support element 3, which is the same as in a conventional pressure sensor. 3 is not tightly bound.

This makes the semiconductor chip 5 independent of any expansions and deformations that the support element 3 will undergo. An absolutely accurate and, above all, constant pressure measurement signal is obtained. Advantageously, the cover element 6 has a thickness that avoids damage.

Further, in the pressure sensor 1 according to the present invention, the semiconductor chip 5 is made of silicon carbide, so-called SOI or, for example, SOS. Advantageously, the mechanical transmission element 8 is also accommodated so as to float inside the cover element 6, in order to further minimize the changes experienced by the pressure signal detected by the pressure sensor 1. .

Further, the mechanical transmission element 8 includes a cover element 6
Are stored in a seat 7. This is because a load is applied in advance, the semiconductor chip 5 is always in contact, and the semiconductor chip 5 is always in a contact state.

Indeed, it has been observed that the pressure sensor 1 according to the invention achieves its intended aim well. This is because much more accurate pressure measurements can be achieved than can be obtained with conventional devices. In addition, the large thickness of the cover element allows the pressure sensor 1 to be protected from damage by the action of the plastic material which would have suffered the frictional film if used on conventional films. The device is applicable to chemical processes and similar processes.

Devices such as those described above are capable of many variations and modifications, all of which are within the scope of the inventive concept, with all details replaced by other technically equivalent elements. Is also good. In fact, it can be done according to the requirements and conditions of the technology, as long as the specifications are as well as the materials and dimensions used. For example, in FIG. 1, the sheet 4 can be positioned and formed by fixing the upper end of the sheet member to the inner edge 3a of the inward flange formed at the top of the hollow support element 3. The cover element 6 is provided with a projection 6a at the center, and a part of the mechanical transmission element 8 is fitted into the sheet 7 on the inner surface of the downwardly facing concave portion of the projection a, so that the Positioning can be done.

[0027]

The present invention is constructed as described above, and ensures high measurement accuracy at all times, and reduces the change and deformation of the measurement signal due to thermal expansion and the like to the minimum level, and achieves high reliability and durability. This has the effect of providing a low-cost pressure sensor that is relatively easy to manufacture.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view at an end of a pressure sensor according to an embodiment of the present invention.

[Explanation of symbols]

1: pressure sensor, 2: outer enclosure, 3: support element, 3a: inner edge, 4: sheet, 5: semiconductor chip, 6: cover element,
6a: protrusion, 7: sheet, 8: mechanical transmission element, 9: strain gauge, 10: metal conductor, 11: reference electrode, 1
2: cylindrical body.

 ──────────────────────────────────────────────────続 き Continuation of front page (71) Applicant 500509025 Via Cave, 11, Prov. of Brescia, 25050 PROV AGLIO D'ISEO, ITALLY (72) Inventor Jose Iseni, Bergamo Brembate 24041, Italy, Viagi. Di Vittorio, 17 (72) Inventor Giovanbattista Preve Italy, Milano Bruggiello 20047, Via Volzulno, 80 (72) Inventor Sergio Doneda, Italy, Brescia Pisogne 25055, Corso Nave Corriera, 8 (72) Inventor Ernst Obermeyer Germany, Day 14050 Berlin, Bolivarary, 6

Claims (7)

[Claims] 1. A support element for a semiconductor chip having a strain gauge on one of the opposite surfaces, an outer enclosure adapted to receive the support element, and a cover provided to close the outer enclosure. An element and a mechanical transmission element housed in the cover element and directed to and in contact with the semiconductor chip, the semiconductor chip being housed in a floating manner in the support element. Pressure sensor characterized by the above-mentioned. 2. The apparatus according to claim 1, wherein the mechanical transmission element housed in the cover element is housed so as to float in a sheet formed in the cover element.
Pressure sensor. 3. The support element comprises alumina, and the support element has a plurality of conductors extending from the support element, the conductors adapted to transmit a pressure signal detected by the strain gauge. The pressure sensor according to claim 1, wherein the strain gauge is disposed on one surface of the semiconductor chip on a side opposite to a surface on which the mechanical transmission element operates. 4. The semiconductor device according to claim 1, wherein the mechanical transmission element is housed in the cover element such that a load is previously applied to a surface of the semiconductor chip on which the mechanical transmission element operates. Item 4. The pressure sensor according to item 3. 5. The pressure sensor according to claim 1, wherein said semiconductor chip is made of silicon carbide. 6. The pressure sensor according to claim 1, wherein said semiconductor chip is made of SOI. 7. The pressure sensor according to claim 1, wherein said semiconductor chip is made of SOS.